The Internet's address system was found to have a critical design flaw that clears the way for any attacker to replace the addresses of Web sites with addresses of malicious servers, security researchers warned on Tuesday. The flaw allows hackers to redirect web pages as they like by using the Domain Name System (DNS).

The Domain Name System is considered to be the Internet's very own address book, which turns hostnames into IP addresses. It is an essential component of the Internet, as it allows users to connect and use Web sites.

This is bad news especially for large businesses and service providers, as the flaw permits hackers' access to unauthorized information. That however doesn't exclude personal computers, which face the same problem.

So far, there have been no reports of somebody actually exploiting the vulnerability, which was accidentally discovered by security researchers. However, security upgrades are a must in order to fix the design flaw.

Dan Kaminsky, director of penetrating testing at IOActive, who discovered the flaw months ago, explained that this is a problem affecting everyone: “Because the system is behaving exactly like it is supposed to behave, the same bug will show up in vendor after vendor after vendor.”

Software companies are currently working on distributing patches to fix the problem. System administrators will have 30 days to apply the patch.

Kaminsky explained that because we are talking about a design flaw, fixing it won't mean pointing at the exact flaw, which should make it hard for hackers to exploit the vulnerability. “We decided that the only way to do this would be a simultaneous release – Microsoft patches, Sun patches, BIND patches, he added.

This vulnerability required simultaneous security upgrades and fixing it was essential in order to protect users from becoming victims of Internet's bad guys.